The present invention relates to an open end wrench capable of fast driving and, more particularly, to an open end wrench capable of fast driving a workpiece without the risk of undesired shifting from the workpiece.
U.S. Pat. No. 1,320,668 discloses a wrench including a stationary jaw and a movable jaw slideable along a guide. The movable jaw is forced against an abutment at an outer end of the guide by a spring bearing against the stationary jaw. An end of the spring is received in a bore in the stationary jaw. The other end of the spring is received in another bore in the movable jaw. An intermediate portion of the spring is exposed between the stationary jaw and the movable jaw. When the user is intended to tighten or loosen a nut, the wrench is turned in a driving direction during which operation the movable jaw remains in contact with the abutment. For reengagement of the wrench with the nut it is necessary only to turn the wrench in the opposite direction, during which operation the movable jaw slides backward against the pressure of the spring and on the edges of the nut. The movable jaw is forced forward again as soon as the bearing surfaces of the stationary and movable jaws are parallel with the sides of the nut. The nut can be tightened or loosened through repeated operations. However, the structural strength of the wrench is insufficient for high-torque operation, as the movable jaw merely encloses the guide and is not enclosed by other members. Furthermore, the guide is irregularly formed in a wrenching space of the wrench, leading to difficulties in processing. Further, the exposed portion of the spring, when compressed by the movable jaw, is liable to bend and, thus, in frictional contact with the end edges of the bores of the stationary and movable jaws, leading to non-smooth compression of the spring or even permanent deformation of the spring. Further, the exposed portion of the spring is apt to be contaminated by oil to which debris easily adheres.
U.S. Pat. No. 3,695,125 discloses an open end ratchet wrench including a head having a fixed jaw and an opposed pawl support portion. A pawl and a spring are mounted to an inner side of the pawl support portion. The pawl is biased by the spring and slideable between an extended torquing position and a retracted ratcheting position. Two side caps are fixed to two sides of the head to define a space receiving the pawl and the spring and to prevent disengagement of the pawl and the spring. The pawl includes a stop shoulder to prevent the pawl from moving out of the pawl support portion under the action of the spring. The pawl support portion includes an arcuate section and then extends perpendicularly to the fixed jaw. Such a structure is difficult to process. Furthermore, assembly of the open end ratchet wrench is troublesome. Further, the pawl is merely enclosed at both sides and has insufficient structural strength in the lateral direction. Further, a contact area of the workpiece (such as a nut) engaged with the movable pawl is smaller than a contact area of the workpiece engaged with the fixed jaw. When the nut is tightened to a position adjacent to an object to be fixed, wear or damage to the nut may occur if the nut has insufficient contact area or has a small volume.
U.S. Pat. No. 4,706,528 discloses an adjustable wrench including a fixed jaw and an adjustable jaw. In an embodiment, a sliding jaw is provided on the fixed jaw. The sliding jaw includes a rectilinearly extending slot through which a pin is extended, preventing disengagement of the sliding jaw. A plate spring is mounted to an inner face of the fixed jaw to bias the sliding jaw outward. A hole is formed in an end wall of the slot and receives a coil spring to bias the sliding jaw inward. Thus, the sliding jaw is movable inward or outward and can be retained in place under action of the plate spring and the coil spring. Such a wrench is particularly suitable for rotating pipes, but not suitable for tightening or loosening fasteners such as bolts, nuts, or the like. This is because the sliding jaw can only slide rectilinearly, and the shape of the slot will cause the sliding jaw to slide along the slot to a position pressing against the periphery of the pipe.
U.S. Pat. No. 7,024,971 discloses an open end ratchet wrench including first and second stationary jaws. The first stationary jaw supports a movable plate. A space is sandwiched between two face plates of the first stationary jaw to accommodate the movable plate. The movable plate includes two angled slots each receiving a pin extending through the space, avoiding disengagement of the movable plate. The wrench further includes a hole receiving a spring that has an end located outside of the hole for biasing the movable plate. Each angled slot of the movable plate includes a short section and a long section at an angle to the short section such that the movable plate can move in two stages each having a rectilinear travel. However, the stationary jaw is enclosed by the movable plate such that the contact area between the stationary jaw and the workpiece is significantly decreased. Instead, the supporting effect depends on the larger contact area between the workpiece and the movable plate with structural strength weaker than the fixed jaw. The holding force applied by the open end ratchet wrench is reduced.
U.S. Publication No. 2009/0193941 A1 discloses first and second jaws formed on a jaw support. The first jaw can be moved by rotating a worm. The jaw support includes an open track in the form of a slot receiving the second jaw. The jaw support further includes a pin extending through the track. The second jaw includes a rectilinear opening through which the pin extends, preventing the second jaw from disengaging from the jaw support. A biasing member is mounted in the opening of the second jaw to bias the second jaw outward. Since the second jaw includes a single rectilinear opening, a change in the spacing from the second jaw to the first jaw is relatively small such that a workpiece will be rotated when the wrench rotates in a reverse direction not intended to rotate the workpiece. Thus, the first jaw must be movable, and the spacing between the first and second jaws can be adjusted by rotating the worm to avoid joint rotation of the workpiece when the wrench rotates in the reverse direction. However, the wrench of this type includes many elements, and the track, opening, and holes in the elements weaken the wrench. Furthermore, since the track is open, the reactive force imparted to the second jaw during driving of the workpiece is completely transmitted to the pin. Thus, the pin is liable to be damaged. Although the second jaw includes a surface in sliding contact with the jaw support to guide sliding movement of the second jaw, this surface merely transmits the reactive force to the pin instead of effectively withstanding the torque. Further, since the second jaw moves rectilinearly, the opening in the second jaw must be lengthened if it is desired to increase the spacing between the first and second jaws. However, this would expose the opening support such that the opening and the biasing member in the opening would easily be contaminated by oil to which debris adheres easily. Furthermore, operation of the biasing member would be adversely affected, causing non-smooth movement of the second jaw.
U.S. Patent Publication No. US 2009/0301271 A1 discloses an open-ended wrench including a first jaw and a second jaw. The second jaw includes an auxiliary jaw retracting opening that receives an auxiliary jaw. A spring is mounted between an end of the auxiliary jaw and an end wall of the auxiliary jaw retracting opening. The auxiliary jaw includes a limiting slot. An auxiliary jaw limiting member extends from a surface of the second jaw through an opening to the auxiliary jaw retracting opening and is coupled with the limiting slot for confining the auxiliary jaw to move between a first position in which the auxiliary jaw is non-longitudinally biased and a second position in which the auxiliary jaw is longitudinally biased. The auxiliary jaw has an arcuate pushing surface and a driving surface. In use, the wrench can drive a nut in a driving direction to a position and then directly move in a reverse direction about the center of the nut. The auxiliary jaw is compressed by a side of the nut and retracts into the auxiliary retracting opening. Thus, the wrench can be directly rotated in the reverse direction through an angle to a next driving position for driving the nut in the driving direction without the need of disengaging from the nut and reengaging with the nut. However, it is difficult to form the auxiliary jaw retracting opening in the second jaw, which is particularly true for axial drilling. Furthermore, the pushing face and the driving surface of the auxiliary jaw must retract into the auxiliary retracting opening so that the wrench can move in the reverse direction to the next driving position. Thus, the widths of the pushing face and the driving surface must be smaller than the size of the auxiliary jaw retracting opening. However, if the nut is of a smaller thickness or if the nut is moved to a position adjacent to a surface of an object to be tightened such that the width of the side of the nut is smaller than the extent of the pushing face and the driving surface, the pushing face and the driving surface may be worn or damaged due to insufficient contact area with the side of the nut.
U.S. Patent Publication No. US 2010/0071516 A1 discloses a reciprocatable open end wrench including first and second jaws and a swing member. The second jaw includes a concave arcuate surface having a slot. The swing member is received in the slot. A surface of the swing member faces the second jaw and has an arcuate hollow groove for receiving a returning device. A retaining pin is inserted into the hollow groove in a manner that allowing the swing member to be slideable relative to the second jaw. The returning device presses against the retaining pin and the swing member and, thus, biases the swing member outward. However, the diameter of the curvature of the concave arcuate face is not concentric to a wrenching width between two parallel sides of a workpiece. After the wrench has driven the workpiece to rotate in a driving direction, the rotating arc of the diameter can not allow the wrench to rotate in a reverse direction to the next driving position. Specifically, the wrench has to be moved backwards through a certain travel so that the concave arcuate face can slide along the side of the workpiece to the next driving position. If the wrench is directly rotated about the center of the workpiece without the backward travel, the arcuate face will be interfered by a side of the workpiece. The driving operation provided by the wrench is not smooth.
Thus, a need exists for an open end wrench capable of fast driving of a workpiece without the disadvantages of the above conventional open end wrenches.